Flame retardant additive for a low smoke, zero halogen compound

ABSTRACT

A low smoke, zero halogen (LSZH) polymer composition is provided. The LSZH polymer composition includes a polymer resin, and a flame retardant package dispersed within the polymer resin. Less than 25% by weight of the polymer composition is the flame retardant package. The flame retardant package includes an acid source, a carbon source, and an LSZH additive. The LSZH additive includes a polyoxometalate ionic liquid and a synergist carrier. The LSZH polymer composition has a limiting oxygen index of greater than 31%. The LSZH polymer compound is suitable for use in electrical or tele-communication cables.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No. 16/193,634filed on Nov. 16, 2018 which is a continuation of InternationalApplication No. PCT/US17/33022 filed on May 17, 2017 which claims thebenefit of priority to U.S. Provisional Application No. 62/341,366,filed on May 25, 2016, all applications being incorporated herein byreference.

BACKGROUND

The disclosure relates generally to flame retardant compounds and moreparticularly to a low smoke, zero halogen compound. Flame retardantmaterials are used to protect combustible materials, such as plastics orwood, from fire damage and heat. Additionally, flame retardant materialshave been used to protect materials that lose their strength whenexposed to high temperatures, such as steel.

SUMMARY

In one aspect, a low smoke, zero halogen (LSZH) polymer composition isprovided. The LSZH polymer composition includes a polymer resin, and aflame retardant package dispersed within the polymer resin. Less than25% by weight of the polymer composition is the flame retardant package.The flame retardant package includes an acid source, a carbon source,and an LSZH additive. The LSZH additive includes a polyoxometalate ionicliquid and a synergist carrier. The LSZH polymer composition has alimiting oxygen index of greater than 31%.

In another aspect, an electrical or tele-communication cable isprovided. The cable includes at least one communication element and apolymeric jacket that surrounds the at least one communication element.The polymeric jacket includes a flame retardant package dispersedthroughout the polymer jacket. The flame retardant package includes anacid source, a carbon source, and an additive. The additive includes apolyoxometalate ionic liquid and a synergist carrier. The polymericjacket has a limiting oxygen index of greater than 30%.

Additional features and advantages will be set forth in the detaileddescription that follows, and in part will be readily apparent to thoseskilled in the art from the description or recognized by practicing theembodiments as described in the written description and claims hereof,as well as the appended drawings.

It is to be understood that both the foregoing general description andthe following detailed description are merely exemplary, and areintended to provide an overview or framework to understand the natureand character of the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding and are incorporated in and constitute a part of thisspecification. The drawings illustrate one or more embodiment(s), andtogether with the description serve to explain principles and theoperation of the various embodiments.

FIG. 1 depicts a schematic representation of a reaction between an ionicliquid cation and a polyoxometalate anion to form a polyoxometale ionicliquid used in a low smoke, zero halogen compound according to anexemplary embodiment;

FIG. 2 depicts a zeolite synergist carrier used in a low smoke, zerohalogen compound according to an exemplary embodiment;

FIG. 3 depicts a graphical representation of the limiting oxygen indexfor a polymer compound incorporating the low smoke, zero halogencompound according to an exemplary embodiment; and

FIG. 4 depicts a cable including one or more components incorporating apolymer compound including the low smoke, zero halogen additiveaccording to another exemplary embodiment.

DETAILED DESCRIPTION

Referring generally to the figures, various embodiments of an additive,such as a low smoke, zero halogen (LSZH) compound suitable for use as,for example, a flame retardant in polymer compounds are provided. TheLSZH additive includes a polyoxometalate ionic liquid combined with asynergist carrier. The LSZH additive is deployed as part of a flameretardant package. In embodiments, the flame retardant package is anintumescent flame retardant package. The LSZH additive can be included,for instance, in a polymer resin. The resulting LSZH polymer resin canbe utilized in such applications as cable jackets for fiber opticcables. However, while fiber optic cables will be discussed as anexemplary embodiment, the LSZH additive can be utilized in a variety ofother contexts and applications.

The LSZH additive is designed to enhance the efficacy of flame retardantcompounds, including intumescent flame retardant compounds, and to limitthe amount of smoke emitted from a polymer (or other matrix) containingthe LSZH additive in the event of a fire. Additionally, the polymercompounds containing the LSZH additive emit very low or no halogens whenexposed to high heat sources. Accordingly, a polymer resin containing anLSZH additive will emit little or no toxic and/or corrosive smoke.

In an embodiment, the LSZH additive is comprised of a polyoxometalateionic liquid and a synergist carrier. As shown in FIG. 1, an ionicliquid cation 10 and polyoxometalate anion 12 are reacted to form apolyoxometalate ionic liquid (PIL) 14. FIG. 1 depicts a reaction betweena 1-butyl-3-methylimidazolium (1+) cation (from the ionic liquid) and aphosphomolybdate ([PMo₁₂O₄₀]³⁻) anion (the polyoxometalate) to form1-butyl-3-methylimidazolium phosphomolybdate (the PIL).

A variety of ionic liquids are suitable for use in the LSZH additive,including 1-ethyl-3-methyl-imidazolium ethylsulfate,1-butyl-3-methylimidazolium hexafluorophosphate,1-butyl-3-methylimidazolium tetrafluoroborate,1-hexyl-3-methylimidazolium hexafluorophosphate,1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide,1-ethyl-3-methylimidazolium trifluoromethanesulfonate, scandium(III)trifluoromethanesulfonate, praseodymium (III) trifluoromethanesulfonate,1,3-dialkyl-1,2,3-triazolium hexafluorophosphate,1,3-dialkyl-1,2,3-triazolium bis(trifluoromethanesulfonyl)imide, and1,2,4-trimethylpyrazolium methylsulfate, among others. Generally, saltscontaining imidazolium cation, quaternary cationic scales, cationicpyrrole, and/or pyrazole cation are suitable ionic liquids for use inthe LSZH additive.

Polyoxometalate anions suitable for use in the LSZH additive include[PW₁₂O₄₀]³⁻, [PMo₁₂O₄₀]³⁻, [SiW₁₂O₄₀]⁴⁻, [SiMo₁₂O₄₀]⁴⁻, [BW₁₂O₄₀]³⁻,[BMo₁₂O₄₀]³⁻, [AsW₁₂O₄₀]⁵⁻, [AsMo₁₂O₄₀]⁵⁻, [GeW₁₂O₄₀]⁴⁻, [GeMo₁₂O₄₀]⁴⁻,[PMo₉V₃O₄₀]⁵⁻, [PMo₁₀V₂O₄₀]⁵⁻, [PMo₁₁VO₄₀]⁴⁻, [P₂W₁₈O₆₂]⁶⁻,[P₂Mo₁₈O₆₂]⁶⁻, [As₂W₁₈O₆₂]⁶⁻, [As₂Mo₁₈O₆₂]⁶⁻, [W₆O₁₉]²⁻, [Mo₆O₁₉]²⁻,[V₆O₁₉]⁸⁻, [Nb₆O₁₉]⁸⁻, among others. In specific embodiments, thepolyoxometalate is selected to contain molybdenum because ofmolybdenum's function as a smoke suppressant.

After reaction of the ionic liquid and polyoxometalate to form the PIL,the PIL is loaded into, or otherwise mixed with, a synergist carrier 16,the crystal structure of which is depicted in FIG. 2. In embodiments,the synergist carrier is an inorganic compound, such as a zeolite, abentonite, and/or zinc borate, among others. The use of the term“synergist” denotes that the synergist carrier operates with thepolyoxometalate ionic liquid to enhance flame and/or smoke suppression.The synergist carrier can do so in a variety of ways, including forminga ceramic layer in or on the char layer/foam, releasing water whendecomposed to dilute the combustible gases and/or to suppress smoke,thermally insulating the polymer compound, functioning as ananti-dripping agent, and/or, together with the polyoxometalate ionicliquid, promoting the function (e.g., the catalytic effect) on thecharring process of the flame retardant package. In a particularembodiment, the synergist is zeolite 4A 18. FIG. 2 depicts the structureof zeolite 4A 18. Zeolite 4A 18 has a pore diameter of 4 Å and a bulkdensity of 0.60-0.65 g/mL. Additionally, zeolite 4A can absorb 20-21%,by weight, of water and exhibits an attrition of 0.3-0.6%, by weight. Inembodiments, the zeolite and polyoxometalate ionic liquid comprisebetween 0.1 to 5% of the total weight of the composition into which theLSZH additive is deployed.

The LSZH additive is deployed as part of a flame retardant package. Theflame retardant package also includes an acid source and a carbonsource. In embodiments, the acid source can be a phosphorous-, boron-,or sulfur-containing chemical. In an embodiment, the acid is aphosphorous-containing chemical, such as ammonium polyphosphate (APP).In embodiments, the carbon source is a polyol, such as pentaerythritol(PER) and/or its derivatives. In other embodiments, the carbon sourcecan include phenol formaldehyde resins, polyamides, sorbitol, starches,and cyclodextrins, among others. The acid source, under heating,decomposes and forms an acid that catalyzes the carbon source tocarbonize and solidify through cross-linking reactions, forming anon-combustible char layer. In embodiments, the ratio of the acid sourceto the carbon source can vary, such as 1:1, 2:1, etc. In an embodimentin which the acid source is APP and the carbon source is PER, an exampleratio of APP:PER is 2:1 or higher.

In still further embodiments, the flame retardant package includes aspumific compound, such as melamine and its derivatives. The spumificcompound forms gases when heated, and the gases cause the solidifiedcarbon (i.e., the char layer created in the carbonization reaction ofthe acid and carbon source) to expand, forming a char foam. The charfoam has a much greater volume than the char layer, which helps insulatethe remaining polymer compound from fire and heat. A flame retardantpackage containing a spumific compound is referred to as intumescentflame retardant package.

The flame retardant package can also include other additives, such asantioxidants, thermal stabilizers, metal hydrates, metal hydroxides(e.g., aluminum trihydroxide and/or magnesium dihydroxide), gas-formingspecies or combinations of species (e.g., melamine and its derivatives,etc.), char strength boosters, and/or other performance enhancingmaterials. In certain embodiments, the acid source, carbon source,and/or spumific compound are combined into a single compound.

In embodiments, the flame retardant package (including the LSZH additiveand any other additives) comprises between 5% and 60% of the totalweight of the compound into which the flame retardant package isdeployed. In other embodiments, the flame retardant package comprisesbetween 10% and 30% of the total weight of the compound into which theflame retardant package is deployed. In a more specific embodiment, theflame retardant package comprises between 15% and 25% of the totalweight of the compound into which the flame retardant package isdeployed.

As discussed above, the LSZH additive has particular suitability forincorporation into a variety of polymer resins, including boththermoplastic and thermosetting polymers. In embodiments, the polymerresin is a thermoplastic, and in a more specific embodiment, thethermoplastic is a polyolefin-based resin. Polymer resins that may beused with the LSZH additive include a single polymer or a blend ofpolymers selected from the following non-limiting list: ethylene-vinylacetate copolymers, ethylene-acrylate copolymers, ethylene homopolymers(including but not limited to low density, medium density, and highdensity), linear low density polyethylene, very low densitypolyethylene, polyolefin elastomer copolymer, propylene homopolymer,polyethylene-polypropylene copolymer, butene- and octene branchedcopolymers, and maleic anhydride-grafted versions of the polymers listedherein.

The polymer resin may also include non-flame retardant additives such asmineral fillers (talc, calcium carbonate, etc.), antioxidants, UVadditives, processing modifiers, compatibilizers, or other standardpolymer additives.

A variety of different processes can be used to incorporate the flameretardant package, including the LSZH additive and any other additives,into the polymer resin. Generally, the incorporation processes utilizeelevated temperature and sufficient shear to distribute the flameretardant package in the polymer resin. Exemplary equipment forincorporating the flame retardant package into the polymer resinincludes a co-rotating twin screw extruder, single screw extruder withmixing zones, a Banbury-style rotary mixer, Buss kneader, and/or otherhigh-shear mixers.

EXAMPLE

In an exemplary embodiment, a PIL for use in the LSZH additive wasprepared from 1-butyl-3-methylimidazolium chloride (an ionic liquid) andammonium phosphomolybadate (a polyoxomolybdate) by ion-exchange reactionin water with the equivalent at 1:1, i.e., stoichiometric amounts. Afterthe 1-butyl-3-methylimidazolium cations are attached to thephosphomolybdate anions, the cations will remain attached to the anionsites while the resulting ammonium chloride is washed away, leaving thePIL 14 as shown in FIG. 1. The achieved PIL was then mixed with zeolite4A in water in a ratio of 1:1.5 of PIL:zeolite 4A, by weight. Theremainder of the flame retardant package included APP as the acid sourceand PER as the carbon source in a ratio of 2:1 of APP:PER, by weight.The flame retardant package, including the LSZH additive, was compoundedwith a polypropylene homopolymer using a twin screw extruder (Leistritz34 mm Twin Screen Extruder). The flame retardant package comprised 20%,by weight, of the polymer compound with the LSZH additive accounting for1% of that weight and the APP/PER accounting for the remaining 19% (theadditive and the APP/PER were mixed prior to compounding). Table 1displays the compounding conditions of the twin screw extruder.

TABLE 1 Compounding Conditions Screw Speed (RPM) 100 Single Feeder(kg/hr) 2.25 Twin Screw Feeder (g/min) 9.4 Zone 1 (° C.) n/a Zone 2 (°C.) 150 Zone 3 (° C.) 180 Zone 4 (° C.) 180 Zone 5 (° C.) 160 Zone 6 (°C.) 160 Zone 7 (° C.) 160 Zone 8 (° C.) 160 Zone 9 (° C.) 160 Zone 10 (°C.) 160 Die Temp (° C.) 150 Torque (amps) 9.1 Vacuum (in/hg) 5

The resulting materials were then injection molded (Arburg 370 C) intotest samples with a processing condition as shown in Table 2.

TABLE 2 Injection Molding Conditions Gate Temp (° C.) 170 Mold TempMoving Half (° F.) 100 Mold Temp Fixed Half (° F.) 100 Temp Zone 1 (°C.) 170 Temp Zone 2 (° C.) 180 Temp Zone 3 (° C.) 190 Temp Zone 4 (° C.)200 Temp Zone 5 (° C.) 200 Dosage Volume (ccm) 20.5 Holding Pressure BarBase 1 (Bar) 900 Holding Time (s) 3 Step 1: Injection Flow (ccm/s) 60Actual Bar Pressure (Bar) 900 Switch Over Point 1.65

Test samples of a polypropylene sample including the LSZH additive(PP-LSZH), a polypropylene sample containing only the APP/PER of theflame retardant package (PP control), and a pure polypropylene sample(PP) were prepared. A visual combustion test was first performed on thepolyproylene samples in which the combustion was triggered using apropane torch. Based on the visual observation, the PP-LSZH sampleperformed significantly better than the PP control sample. Additionally,the PP-LSZH sample showed a low volume expansion of the resulting charresidue.

The polypropylene samples were also tested to determine their limitingoxygen index (LOI) and their UL-94 rating on a vertical burning test.The LOI of a polymer indicates the minimum concentration of oxygen thatwill support combustion of that polymer. Thus, for flame retardantmaterials, a higher LOI indicates a higher flame retardance. The UL-94vertical burning test determines how long a suspended polymer specimenwill burn when the polymer specimen is exposed to flame from below. Thebest rating under UL-94 is V-0 and corresponds to a material that doesnot exhibit a burning flame for more than 10 seconds after being litfrom the flame source below the sample. Additionally, a polymer with aV-0 rating will not experience dripping flames from the sample. Theresults of the testing are displayed in Table 3. (“NR” as used in Table3 means that the sample was not rated).

TABLE 3 Flame Retardant Properties of Polypropylene Samples APP/ PIL/ PPPER zeolite 4A LOI Samples (wt %) (wt %) (wt %) (%) UL-94 Dripping PP100 0 0 18.0 NR Yes PP control 80 20 0 23.2 NR Yes PP-LSZH 80 19 1 32.4V-0 No

Table 3 demonstrates that the addition of the LSZH additive improved theflame retardance of the polypropylene polymer. PP-LSZH possesses a fireperformance of V-0 (non-dripping) in the UL-94 test and an LOI of 32.4%.By comparison, the PP control sample, which included 1% higher amount ofthe flame retardant package and no PIL and zeolite 4A, exhibited an LOIof 23.2% and a UL-94 rating of “not rated” (i.e., the sample exhibiteddripping flames). The results of LOI test are summarized graphically inFIG. 3.

Advantageously, flame retardant package with the LSZH additive providesthese enhancements while only being loaded into the polymer compound at20% by weight. Accordingly, the flame retardant package with the LSZHadditive does not have a substantial impact on the mechanical propertiesof the polymer resin.

It is surmised that the LSZH additive significantly improves theefficacy of flame retardant compositions (and more specifically ofintumescent compositions) by its catalytic effect on the charringprocess, i.e., by making the carbonization faster and the formed charresidue denser. More specifically, it is surmised that a synergismexists between the zeolite 4A and the PIL that enables the catalyticeffect. Regardless of the mechanism, the LSZH provides better flameretardance as evidenced by the results summarized in Table 3 and FIG. 3.Accordingly, using the LSZH additive could allow for reduced loading ofa given polymer resin while maintaining the same flame retardantperformance, which can provide a material cost savings. Alternatively,the LSZH can allow for increased flame retardant performance at the sameloading, which may allow for improved burn performance ratings thanpreviously achieved.

The flame retardant polymer composition, including the LSZH additive, asdescribed herein can be used for a variety of applications. Forinstance, the polymer composition can be added to wood or steel beamsand to the walls of a structure to provide a fire retardant coating.

In a particular embodiment as shown in FIG. 4, the flame retardantpolymer composition, including the LSZH additive, is used as a jacketfor a cable or other fiber optic cable components. Various fiber opticcable components include or, in some embodiments, are made from polymercompounds that are based on polyolefin and olefin copolymers. Withoutmodification, these polyolefin and olefin copolymers are combustible.Accordingly, incorporating the LSZH additive to the polymers that makeup fiber optic cable components is expected to reduce combustibility.

By way of example of how and where the LSZH additive can beincorporated, FIG. 4 depicts a fiber optic cable 20, including the LSZHadditive. Cable 20 includes a cable body, shown as cable jacket 22,having an inner surface 24 that defines a channel, shown as central bore26. Pluralities of communication elements, shown as optical fibers 28,are located within bore 26. The cable 20 includes a plurality of coreelements located within central bore 26. A first type of core element isan optical transmission core element, and these core elements includebundles of optical fibers 28 that are located within tubes, shown asbuffer tubes 30. Buffer tubes 30 are arranged around a central support,shown as central strength member 34. Central strength member 34 includesan outer coating layer 36. A barrier material, such as water barrier 38,is located around the wrapped buffer tubes 30. An easy access structure,shown as rip cord 39, may be located inside cable jacket 22 tofacilitate access to buffer tubes 30.

In one embodiment, the flame retardant package, including the LSZHadditive, is incorporated into the polymer material of cable jacket 22of fiber optic cable 20. In another embodiment, the flame retardantpackage, including the LSZH additive, is incorporated into the polymermaterial of buffer tubes 30 surrounding the bundles of optical fibers28. In a further embodiment, the flame retardant package, including theLSZH additive, is incorporated into the water barrier 38. By surroundingthe cable and cable components with the flame retardant package,including the LSZH additive, the ability of fire to spread along cable20 is reduced, and the amount of smoke produced by cable 20 during fireexposure is also reduced.

It is believed that the flame retardant package, including the LSZHadditive, discussed above will meet certain flame retardant standardswhen incorporated in an electrical or tele-communication cable, such ascone calorimeter reaction-to-fire test ISO 5660; limiting oxygen index(LOI) test ISO 4589; single cable test IEC 60332-1-2; vertical multicable test DIN 50399/IEC 60332-3-24; and in smoke density chamber IEC61034.

Unless otherwise expressly stated, it is in no way intended that anymethod set forth herein be construed as requiring that its steps beperformed in a specific order. Accordingly, where a method claim doesnot actually recite an order to be followed by its steps or it is nototherwise specifically stated in the claims or descriptions that thesteps are to be limited to a specific order, it is in no way intendedthat any particular order be inferred. In addition, as used herein, thearticle “a” is intended to include one or more than one component orelement, and is not intended to be construed as meaning only one.

It will be apparent to those skilled in the art that variousmodifications and variations can be made without departing from thespirit or scope of the disclosed embodiments. Since modifications,combinations, sub-combinations and variations of the disclosedembodiments incorporating the spirit and substance of the embodimentsmay occur to persons skilled in the art, the disclosed embodimentsshould be construed to include everything within the scope of theappended claims and their equivalents.

What is claimed is:
 1. An electrical or tele-communication cablecomprising: at least one communication element; a polymeric jacket thatsurrounds the at least one communication element; wherein the polymericjacket includes a flame retardant package dispersed throughout thepolymer jacket and wherein the flame retardant package comprises: anacid source; a carbon source; and an additive, comprising: apolyoxometalate ionic liquid; and a synergist carrier comprising azeolite, wherein the polymeric jacket has a limiting oxygen index ofgreater than 30%.
 2. The cable of claim 1, wherein the at least onecommunication element comprises an optical fiber.
 3. The cable of claim1, wherein the cable achieves a rating of V-0 according to UL-94vertical burn test.
 4. The cable of claim 1, wherein the flame retardantpackage dispersed throughout the polymer jacket comprises no more than35%, by weight, of the polymeric jacket.
 5. The cable of claim 1,wherein the zeolite comprises zeolite 4A.
 6. The cable of claim 1,wherein the additive dispersed throughout the polymer jacket comprisesbetween 0.5 and 5%, by weight, of the polymeric jacket.
 7. The cable ofclaim 1, wherein the acid source is ammonium polyphosphate (APP) and thecarbon source is pentaerythritol (PER) and wherein the weight ratio ofAPP:PER is at least 2:1.
 8. The cable of claim 1, wherein thepolyoxometalate ionic liquid is formed from an ionic liquid selectedfrom the group consisting of 1-ethyl-3-methyl-imidazolium ethyl sulfate,1-butyl-3-methylimidazolium hexafluorophosphate,1-butyl-3-methylimidazolium tetrafluoroborate,1-hexyl-3-methylimidazolium hexafluorophosphate,1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide,1-ethyl-3-methylimidazolium trifluoromethanesulfonate, scandium(III)trifluoromethanesulfonate, praseodymium (III) trifluoromethanesulfonate,1,3-dialkyl-1,2,3-triazolium hexafluorophosphate,1,3-dialkyl-1,2,3-triazolium bis(trifluoromethanesulfonyl)imide,1,2,4-trimethylpyrazolium methyl sulfate, and combinations thereof. 9.The cable of claim 1, wherein the polyoxometalate ionic liquid is formedfrom a polyoxometalate selected from the group consisting of[PW₁₂O₄₀]³⁻, [PMo₁₂O₄₀]³⁻, [SiW₁₂O₄₀]⁴⁻, [SiMo₁₂O₄₀]⁴⁻, [BW₁₂O₄₀]³⁻,[BMo₁₂O₄₀]³⁻, [AsW₁₂O₄₀]⁵⁻, [AsMo₁₂O₄₀]⁵⁻, [GeW₁₂O₄₀]⁴⁻, [GeMo₁₂O₄₀]⁴⁻,[PMo₉V₃O₄₀]⁵⁻, [PMo₁₀V₂O₄₀]⁵⁻, [PMo₁₁VO₄₀]⁴⁻, [P₂W₁₈O₆₂]⁶⁻,[P₂Mo₁₈O₆₂]⁶⁻, [As₂W₁₈O₆₂]⁶⁻, [As₂Mo₁₈O₆₂]⁶⁻, [W₆O₁₉]²⁻, [Mo₆O₁₉]²⁻,[V₆O₁₉]⁸⁻, [Nb₆O₁₉]⁸⁻, and combinations thereof.
 10. The cable of claim1, wherein the synergist carrier further comprises at least one of abentonite or zinc borate.
 11. The cable of claim 1, wherein the carbonsource is selected from the group consisting of pentaerythritol and itsderivatives, phenol formaldehyde resins, polyamides, sorbitol, starches,cyclodextrins, and combinations thereof.
 12. The cable of claim 1,wherein the polymer jacket comprises a polymer resin selected from thegroup consisting of ethylene-vinyl acetate copolymers, ethylene-acrylatecopolymers, ethylene homopolymers, linear low density polyethylene, verylow density polyethylene, polyolefin elastomer copolymer, propylenehomopolymer, polyethylene-polypropylene copolymer, butene and octenebranched copolymers, maleic anhydride-grafted versions of the polymerslisted herein, and combinations thereof.
 13. The cable of claim 1,wherein the flame retardant package further comprises a spumificcompound.
 14. The cable of claim 13, wherein the spumific compoundincludes melamine.
 15. The cable of claim 1, wherein the polymericjacket comprises less than 25% by weight of the flame retardant packageand wherein the limiting oxygen index is greater than 31%.
 16. The cableof claim 1, wherein the flame retardant package further comprises atleast one of aluminum trihydroxide or magnesium dihydroxide.